JP2005343434A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably and exactly perform tension adjustment by a collar by making fixing of the collar, i.e., a tension adjustment member of a belt to double-fixing of fixing by a bolt and fixing by a knock pin. <P>SOLUTION: The tension adjustment of a belt 8c is performed by pivoting in an adjustment area L of a long hole of a second bolt insertion hole A21b making a first bolt insertion hole A21a of the collar 11 for rotatably supporting an input pulley 8a as fulcrum and tension of the belt 8c is adjusted by moving a rotation axis of the input pulley 8a from D1 to D2 by pivoting of the collar 11. The double-fixing of fixing of the collar 11 to a collar support member by a bolt in the long hole and fixing of the collar 11 and the collar support member by the knock pin is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric power steering apparatus for a vehicle, and more particularly to an improvement technique of a tension adjustment mechanism for a driving belt in an electric power steering apparatus adopting a belt driving system.

  In an electric power steering apparatus that performs steering by applying an auxiliary steering force for steering by an electric motor to a steering force by an operation of a steering wheel, the pulley provided on the electric motor shaft and the ball screw shaft of the rack shaft rotate. A belt is stretched between pulleys provided on the fitted ball nut, and a driving force for applying an auxiliary steering force of the electric motor is transmitted from the ball nut to the rack shaft via the belt, thereby the steering. 2. Description of the Related Art A belt-driven electric power steering device in which the auxiliary steering force is applied to the steering force by the operation of is known in the past, and in such an electric power steering device, the tension of the belt is adjusted. For example, a device including an adjustment mechanism is known (for example, see Patent Document 1).

JP 2003-220959 A (page 3-5, FIGS. 3 and 5)

  In the electric power steering apparatus employing the belt drive system described in Patent Document 1, the tension adjustment of the belt 01 described above is performed by adjusting the holding housing 03 of the input pulley 02 and the output pulley 04 as shown in FIG. The relative position adjustment between both housings 03 and 05 is performed by adjusting the relative position between the two housings 03 and 05, and the shims at the housing contact portions of both housings 03 and 05 are performed. This is performed by interposing a spacer member 06 such as.

Further, in another embodiment shown in FIG. 10, the connecting housing for holding the input pulley 02 and the motor housing 03 are pulled up by the screwing operation of the drive bolt 07, and the input pulley 02 and the center of the output pulley (not shown) are arranged. The tension of the belt 01 is adjusted by increasing the distance between the axes.

Furthermore, although not shown in the figure, as another aspect, a movable housing having a circular hole formed in the fixed housing and a circular outer diameter portion supported in the circular hole so as to be capable of adjusting the rotational position is provided. An eccentric hole is formed at a position deviated from the center of the circular outer diameter portion of the movable housing, and the shaft is located at the center of the hole, and an input pulley is provided to support a rotatable shaft. The movable shaft is provided with a structure, and the movable shaft is rotated by a predetermined amount so that the rotatable shaft provided with the input pulley is eccentrically moved to adjust the belt tension. After the adjustment, the movable housing is moved relative to the fixed housing by a lock nut. Some are designed to be fixed.

By the way, the tension adjustment of the belt by interposing a spacer such as the above-mentioned shim is to loosen the tightening bolt between the two housings, select a shim having an appropriate thickness, and insert it between the contact portions of the two housings. Therefore, the workability for adjustment is not always good.

Also, the belt tension adjusting mechanism by screwing the drive bolt and the belt tension adjusting mechanism by rotating the movable housing that supports the shaft of the input pulley by its eccentric hole are provided between the pulley shafts by loosening of the drive bolt and lock nut. The loss of the distance holding function may occur, and the occurrence of such a situation will cause the loss of normal meshing in the toothed belt and make it impossible to apply the steering assist force. In such a tension adjusting mechanism, special measures are taken to prevent loosening of bolts and locknuts. However, there is no good measure that can effectively prevent the above-described situation from occurring and can be provided simply and at low cost.

Under such circumstances, in the belt-driven electric power steering apparatus as described above, the occurrence of the above-described situation due to the loosening of the bolts and locknuts during belt tension adjustment can be effectively and reliably prevented. It is desired to provide an improved structure of a belt tension adjusting mechanism that can be provided at low cost by a simple structural change.

  The present invention relates to an improved structure of a belt tension adjusting mechanism in an electric power steering apparatus for solving the above-described problems, and provides an auxiliary steering force by driving an electric motor to a steering force by steering operation via a belt transmission means. In the electric power steering apparatus that performs steering, the belt transmission means includes a belt tension adjusting unit, and the belt tension adjusting unit is a collar that rotatably supports an input pulley attached to the electric motor shaft. The belt tension is adjusted by adjusting the relative position of the collar with respect to the collar mounting member and fixing the bolt of the collar to the collar mounting member after the position adjustment. And fixing by a knock pin.

Further, in the electric power steering apparatus that performs steering by giving an auxiliary steering force by driving of the electric motor to the steering force by the steering operation through the belt transmission means, the belt transmission means includes a belt tension adjusting unit. The belt tension adjusting unit is a rotating collar that rotatably supports the input pulley attached to the electric motor shaft at the eccentric position, and the belt tension adjustment by the rotating collar is performed by the rotating collar. The relative position adjustment with respect to the collar support member at the eccentric position by the rotation with respect to the collar support member, and the fixing of the rotation collar with respect to the collar support member after the position adjustment by the lock nut and the fixing with the knock pin, To do.

  According to a first aspect of the present invention, in the electric power steering apparatus, the belt transmission means includes a belt tension adjusting unit, and the belt tension adjusting unit rotates an input pulley attached to the electric motor shaft. It is a long hole provided in the collar that is freely supported, and the belt tension adjustment by the long hole is performed by adjusting the relative position of the collar with respect to the collar mounting member by the long hole and the color mounting member after the position adjustment. Since the collar bolt is fixed by screwing and using a dowel pin, the structure for adjusting the belt tension is simple, the adjustment work is easy and easy, and the fixing after adjustment is screwed in. Because of the double fixing of fixing with the dowel pin and fixing with the knock pin, a strong fixing state can be obtained. Further, even if a situation occurs in which the screwing of the bolt is loosened, the adjusted belt tension is stably maintained.

According to a second aspect of the present invention, in the electric power steering apparatus, the belt transmission means includes a belt tension adjusting unit, and the belt tension adjusting unit is an input pulley attached to an electric motor shaft. The belt is adjusted by the rotating collar so that the belt tension is adjusted relative to the collar supporting member at the eccentric position by rotating the rotating collar with respect to the collar supporting member. Since the position is adjusted and the collar support member is fixed to the collar support member by the lock nut and the knock pin, the structure for adjusting the belt tension is relatively simple. Is simple because the rotating collar only needs to be rotated, and its workability is good. In addition, fixing the rotating collar after adjustment is strong because it is a double fixing with tightening with a lock nut and fixing with a knock pin, even if a situation where the lock nut is loosened occurs. The tension is kept stable.

  Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall view of a power steering apparatus for a vehicle according to the present invention. This power steering apparatus is provided with a steering wheel (not shown in FIG. 1) operated by a driver and a steering force applied to the steering wheel. A gearbox 1 that is input via an interlocking mechanism having a shaft, a transmission mechanism that transmits a steering force from the gearbox 1 to a steering wheel, and an electric motor 2 that generates an auxiliary steering force that assists the steering force by the driver. And an auxiliary steering force input unit 3 provided.

The gear box 1 is attached to the vehicle body, the gear housing 4, the input portion 1a to which the steering force from the steering wheel is input, the housing 1 is accommodated in the gear housing 4, and the input portion 1a. An output unit (not shown in FIG. 1) that includes a conversion mechanism that is connected and converts the direction of the steering force from the input unit 1a is provided.

The gear housing 4 includes cylindrical first and second housings 41 and 42 that are coupled to each other at their end portions and are accommodated across a rack shaft 5 described later. In the longitudinal direction of the rack shaft 5, the one end portion 41 a of the first housing 41 is provided with an input portion 1 a to which a steering force from the handle is input and a mounting portion 41 b that accommodates a part thereof. The other end portion 41c is provided with one forming wall 41d of the accommodating portion 43 that forms a transmission chamber in which a transmission mechanism 8 described later is accommodated.

One end of the second housing 42 is provided with the other forming wall 42b of the accommodating portion 43 that forms a transmission chamber in cooperation with the one forming wall 41d.
The pair of housing portion forming walls 41d and 42b are respectively a part of the housings 41 and 42 made of a single member, and the peripheral portions of the forming walls 41d and 42b are coupled by a plurality of bolts B. Parts.

Referring to FIG. 2, there is shown an outline of the operation in the steering operation of the steering apparatus. The input unit 1a includes an input shaft 1b that is rotationally driven by a handle H via a linkage mechanism, and a torsion bar 1c. And an output shaft 1d coupled to the input shaft 1b so as to be relatively rotatable, and a torque sensor 1e for detecting a steering torque based on a torsion amount of the torsion bar 1c.

The conversion mechanism includes a pinion 1f as a rotation driving portion formed on the output shaft 1d, a rack portion 5a as a driven portion driven by the pinion 1f, and a rack as a steering member on which the rack portion 5a is formed. A shaft 5 is provided. The rack shaft 5 extends in the left-right direction of the vehicle when the steering device is mounted on the vehicle, and is driven by the rotating input shaft 1b by the rack and pinion mechanism including the pinion 1f and the rack portion 5a. A reciprocating linear motion is performed in the longitudinal direction in the first and second housings 41 and.

The transmission mechanism includes a pair of tie rods 7 connected to both ends of the rack shaft 5 via ball joints 6 and a link mechanism (not shown) connected to each tie rod 7. Then, the steering force from the rack shaft 5 is transmitted through the tie rods 7 and the link mechanism, and acts on each steered wheel of the vehicle (not shown), thereby turning the steered wheel.

An auxiliary steering force input unit 3 that applies an auxiliary steering force to the rack shaft 5 at the time of turning is an electric motor 2 as a rotary actuator that is controlled by an electronic control unit 1g to which a steering torque detected by a torque sensor 1e is input. A belt type transmission mechanism 8 to which an auxiliary steering force generated by the electric motor 2 is input, a ball screw mechanism 9 as a transmission mechanism for transmitting the output of the transmission mechanism 8 to the rack shaft 5, and a belt described later of the transmission mechanism 8. An adjustment unit 10 (not shown in FIG. 2) for adjusting the tension of 8c is provided.

Referring also to FIG. 3, the electric motor 2 coupled via the collar 11 to the mounting portion 41 e constituted by a part of the one forming wall 41 d of the accommodating portion 43 includes a flange for coupling to the collar 11. A cylindrical housing 2b having a mounting portion 2a and a rotating shaft 2A for rotating and driving an input pulley 8a to be described later are provided. In the electric motor 2, a pair of bolts B <b> 1 and B <b> 2 that are respectively inserted into a pair of insertion holes 2 d provided at positions facing the attachment portion 2 a across the rotation center line of the rotation shaft 2 </ b> A are provided in the collar 11. When the collar 11 is screwed into the pair of screw holes A11a and A11b (see FIG. 5), the collar 11 and the formation wall 41d are attached via the collar 11 so that the rotation center line is substantially parallel to the longitudinal direction. It is attached to the part 41e.

The transmission mechanism 8, which is also a speed reduction mechanism, includes an input pulley 8 a whose shaft portion 8 A is connected to the electric motor shaft 2 A via a shaft joint 12 and driven to rotate by the motor, and a rack shaft 5 via a ball screw mechanism 9. An output pulley 8b to be connected, and an input pulley 8a and a belt 8c made of a toothed belt stretched over an output pulley 8b having a larger diameter than the input pulley 8a are provided.
An input pulley 8a as an input portion of the transmission mechanism 8 includes a columnar main body portion 8a1 on which a belt 8c is hung, and a pair of shaft portions 8A extending in parallel to the rotation center line of the input pulley 8a with the main body portion 8a1 interposed therebetween. Prepare.

The pair of shaft portions 8A is rotatably supported by the pair of bearing portions of the collar 11 via bearings 13 and 14 formed of radial ball bearings. An output pulley 8b as an output portion of the transmission mechanism 8 includes a cylindrical main body portion 8b1 on which a belt 8c is hung, and a cylindrical shaft portion 8B extending from the main body portion 8b1 in parallel to the rotation center line of the output pulley 8b. Is provided.
Note that tooth portions 8a2 and 8b2 having a large number of teeth meshing with the teeth of the belt 8c are formed on the outer peripheral surfaces of the body portions 8a1 and 8b1 of the input pulley 8a and the output pulley 8b, respectively.

Referring to FIG. 4, the shaft coupling 12 is connected to an input member 12A coupled to the motor shaft 2A via the ring 2A1 (see FIG. 3) so as to be integrally rotatable, and a shaft portion 8A (see FIG. 3) of the input pulley 8a. An output member 12B coupled so as to be integrally rotatable, and an elastic body that is interposed between the input member 12A and the output member 12B to drive-couple them, for example, a buffer member made of synthetic rubber that is an elastic body exhibiting rubber-like elasticity As a bush 12C.

The bush 12C is sandwiched between a plurality of teeth 12A1 and 12B1 provided on the input member 12A and the output member 12B in the circumferential direction, and reliably transmits the torque of the electric motor 2 to the input pulley 8a. Torque fluctuations are alleviated and noise in the shaft coupling 12 is prevented.

Referring to FIG. 3 again, a ball screw mechanism 9 as a motion converting mechanism for converting the rotational motion of the output pulley 8b into the linear motion of the rack shaft 5 includes a ball screw shaft portion 5b formed on the rack shaft 5 and a ball screw. The ball nut 9a is disposed so as to surround the shaft portion 5b, the screw groove 5c formed on the outer peripheral surface of the ball screw shaft portion 5b, and the screw groove 9b formed on the inner peripheral surface of the ball nut 9a. A large number of rolling balls 9c.

A group of balls 9c roll on a return path (not shown) provided in the ball nut 9a and circulate between the ball screw shaft portion 5b and the ball nut 9a. The ball nut 9a accommodated in the transmission chamber is rotatably supported by the accommodating portion 43 via a bearing 9e formed of a double row angular ball bearing fixed to the accommodating portion by an annular first lock nut 9d. In the ball nut 9a, the shaft portion 8B of the output pulley 8b and the bearing 9e are arranged in series on the outer peripheral surface in the direction of the rotation center line of the nut 9a, and in the direction of the rotation center line by the second lock nut 9f. Are coupled in a state in which the movement is blocked. Thereby, the ball nut 9a rotates integrally with the output pulley 8b so as to have a rotation center line coinciding with the rotation center axis of the output pulley 8b.

As can be understood with reference also to FIG. 6, the cylindrical collar 11 has a large size for mounting the electric motor 2 and attaching the collar 11 itself to the housing portion forming wall 41 d of the transmission mechanism of the first housing 41. A first mounting portion 11A1 (see FIG. 6) on which the electric motor 2 is mounted with an annular mating surface with the flange-shaped mounting portion 2a of the electric motor 2; A large-diameter having a second attachment portion 11A2 (see FIG. 6) having an annular mating surface with the attachment portion 41e of the formation wall 41d of 43 and attaching the collar 11 itself to the attachment portion 41e of the accommodation portion formation wall 41d. 11A, and a support member 11B (described later) that rotatably supports the input pulley 8a.

The first mounting portion 11A1 is provided with a pair of screw holes A11a and A11b in the pair of coupling sites A11, respectively, and the second mounting portion 11A2 in the circumferential direction of the collar 11 and in the circumferential direction of the pair of coupling sites A11. In each of the screw holes A11a and A11b, a pair of coupling sites A21 formed of stepped portions A0 that are formed at positions adjacent to each other in the rotational axis direction of the pulley 8a and retreating from the mating surface toward the mating surface. A pair of first and second bolt insertion holes A21a, A21b are provided at intervals in the circumferential direction.

As can be understood by referring to FIG. 6, the coupling site A11 for mounting the motor 2 and the coupling site A21 for mounting the collar 11 are radially outward at the first mounting portion 11A1 and the second mounting portion 11A2, respectively. It is the protrusion part which protruded in.

Returning to FIG. 3, the support portion 11 </ b> B of the collar 11 includes a bearing portion that holds the large-diameter bearing 13 and a bearing portion that holds the small-diameter bearing 14 in the order closer to the attachment portion 11 </ b> A in the rotation axis direction. The input pulley 8a in which the output member 12B of the shaft coupling 12 is coupled to the shaft portion 8A has a toothed belt 8c hung on a body portion 8a1 having a tooth portion 8a2 formed on the outer peripheral surface thereof, and the body portion 8a1. The belt guide members 15 are respectively disposed between the bearings 13 and 14, and both the bearings 13 and 14 are prevented from moving in the rotational axis direction by the locking means 16 with respect to the bearing portions. It is supported by the support part 11B via the bearings 13 and 14. At this time, the belt 8c extends to the outside of the collar 11 through the opening 11B1 of the support portion 11B provided partially in the circumferential direction between the bearings 13 and 14.
The present invention can be applied not only to a belt-driven transmission power steering device but also to a gear-driven transmission power steering device.

The collar 11 supports the input pulley 8a on which the belt 8c is hung by the support portion 11B, and bolts B3 and B4 (for adjustment), which will be described later, are inserted through the coupling portion A21 of the second attachment portion 11A2. In the state of being inserted into the holes A21a and A21b (see FIGS. 5 and 6), from the arrangement side of the electric motor 2, the through hole 41f provided in the housing portion forming wall 41d of the first housing 41 is penetrated into the transmission chamber. A pair of screw holes 41e1 and 41e2 provided in the collar mounting portion 41e of the forming wall 41d are provided with adjustment bolts B3 and B4 that are arranged and inserted into the first and second bolt insertion holes A21a and A21b in the coupling site A21. By being screwed into each of them (see FIG. 5), the first housing 41 is attached to the collar attaching portion 41e of the forming wall 41d.

In this manner, the input pulley 8a is rotatably supported by the collar 11 as the input side support member, and the output pulley 8b is rotated by the formation wall 41d of the housing portion 43 as the output side support member or the first housing 41. Supported as possible.

The belt tension adjusting unit 10 can adjust the center-to-center distance, which is the distance between the rotation center lines parallel to each other, and the tension of the belt 8c can be adjusted by adjusting the center-to-center distance by the adjusting unit 10. Is set.

The adjustment portion 10 is configured by a coupling portion A21 that forms a pair with the second attachment portion 11A2 of the collar 11, that is, more specifically, the attachment portion forming wall 41d of the first housing 41 to the collar attachment portion 41e. It is comprised by 1st, 2nd volt | bolt penetration hole A21a, A21b in a pair of coupling | bond part A21 which is a protrusion part which protrudes in the radial direction outward from 2nd attachment part 11A2 which is a part.
Referring to FIG. 6, the first bolt insertion hole A21a formed in the left side coupling portion of the pair of coupling portions A21 of the collar 11 is a normal circular bolt insertion hole, The second bolt insertion hole A21b formed in the coupling portion on the side is a long hole.

The collar 11 in the normal state, that is, not in the state of adjustment work, is attached to the collar 11 by inserting the adjustment bolt B3 into the circular first bolt insertion hole A21a in the coupling portion A21 on the left side in FIGS. The adjustment bolt B4 is inserted into the second bolt insertion hole A21b, which is a long hole in the coupling portion A21 on the right side of the drawing, and is screwed into the screw hole 41e2 of the collar mounting portion 41e. The collar 11 is formed with a mounting portion of the receiving portion 43, that is, a receiving portion of the transmission mechanism of the first housing 41, at a coupling portion A 21 that is symmetrical with respect to the rotation axes of the two input pulleys 8 a on the left and right sides. It is fixed to the collar mounting portion 41e of the wall 41d.

And the long hole which is the 2nd volt | bolt insertion hole A21b formed in the illustration right side coupling | bond part A21 of the collar 11 which comprises the tension | tensile_strength adjustment | control part 10 of the belt 8c substantially in the illustration left side coupling | bond part A21 of the collar 11 is shown. A predetermined length located on the circumference of a predetermined circle drawn by the swing motion of the collar 11 with the formed circular first bolt insertion hole A21a as the swing center, and a width through which the adjustment bolt B4 is easily inserted Formed as a hole.

The tension adjustment of the belt 8c is performed in a state where the electric motor 2 is detached from the collar 11, and in the left and right coupling portion A21 of the second mounting portion 11A2 of the collar 11, that is, the accommodating portion forming wall 41d of the first housing 41. The adjustment bolts B3 and B4 inserted into the first and second bolt insertion holes A21a and A21b described above at the left and right coupling part A21 which is the collar mounting portion to the screw are allowed to move for adjusting the collar 11, respectively. As shown in FIG. 7, the collar 11 receives the circular first bolt insertion hole A21a of the left coupling portion A21 as shown in FIG. Relative to the first housing 41 having a reference), the second bolt insertion hole A21b is swung by a predetermined amount within the adjustment range L allowed by the length of the long hole. In it is made.

If the appropriate adjustment position of the belt tension is determined by adjusting the distance D1 between the rotation centerlines O1 and O2 of the output pulleys 8a and 8b and the adjustment from the distance D1 to D2 when the collar 11 is swung, the left and right coupling portion A21 is determined. Adjustment bolts B3 and B4 inserted through the first and second insertion holes A21a and A21b are respectively screwed into the screw holes 41e1 and 41e2 (see FIG. 5) of the collar mounting portion 41e of the housing portion forming wall 41d. The collar 11 is fixed to the collar mounting portion 41e of the forming wall 41d, that is, to the first housing 41.

After the collar 11 is fixed by the adjusting bolts B3 and B4, as shown in FIG. 3, the second mounting portion 11A2 of the second mounting portion 11A2 is aligned with the housing portion forming wall 41d of the first housing 41 as shown in FIG. A hole X1 is opened by a drill from the attachment side of the electric motor 2 in the surface equivalent portion, and this hole X1 is connected to the collar 11 and a pulley rotation axis that penetrates the thick portion corresponding to the housing portion forming wall 41d of the first housing 41. These are parallel holes X1, and knock pins 17 are driven into the through holes X1 to fix the collar 11 more firmly to the accommodating portion forming wall 41d of the first housing 41. Thereby, the tension adjustment of the belt 8c spanned between the input pulley 8a and the output pulley 8b is completely completed.

After the adjustment, that is, after the adjustment of the tension of the belt 8c, after the adjustment bolts B3 and B4 are screwed into the accommodating portion forming wall 41d of the collar 11 and fixed with the knock pin 17, the collar 11 is removed before the adjustment operation. A motor 2 is attached.

Although the mounting of the electric motor 2 has already been described partially, the annular protrusion 2c on the motor shaft 2A side of the cylindrical motor housing 2b is fitted to the annular inner peripheral surface of the large-diameter mounting portion 11A of the collar 11. At the same time, the motor shaft 2A is connected to the shaft portion 8A of the input pulley 8a via an elastic joint portion 12C made of a rubber-like elastic body or the like, and the flange-like mounting portion 2a of the motor housing 2b is a large-diameter mounting portion of the collar 11. The bolts B1 and B2 are screwed into and fixed to the screw holes A11a and A11b (see FIGS. 5 and 6) in the coupling portion A11 forming the pair of the collars 11 in contact with the annular mating surface of the first mounting portion 11A1 of 11A. Is done.

  And since the annular protrusion 2c of the motor housing 2b is positioned in the vicinity of the head of the knock pin 17 driven by the attachment of the electric motor 2, the knock pin 17 is prevented from coming off.

  Referring to FIG. 8, there is shown another embodiment 2 of the electric power steering apparatus of the present invention. This power steering apparatus has the same structure as that of the steering apparatus of the first embodiment described above, but differs in the arrangement structure of the electric motor 2 and the structure in the vicinity thereof. For example, the electric motor 2 includes the gear housing 4. It can be mounted from the opposite direction to the steering force input side. Characteristically, the structure of the tension adjusting portion 10 of the belt 8c is different. Therefore, the description in the second embodiment is centered on the structure of the tension adjusting portion 10 of the belt 8c, and the other structural portions are omitted. In addition, about the member which is a little different in the structure, but is identified, the same name and the same code | symbol are used for convenience.

FIG. 8 is a diagram showing an enlarged cross-sectional view of the structure near the portion where the electric motor 2 is disposed.
The electric motor 2 is attached to the formation wall 42b with the flange-like attachment portion 2a of the cylindrical housing 2b coming into contact with one annular mating surface of the transmission mechanism accommodating portion formation wall 42b of the second housing 42. The motor shaft 2 </ b> A is extended so as to face the accommodating portion 43.
Then, the first and second housings 41 and 42 are fixed to each other by abutting the annular mating surface of the housing portion forming wall 41d of the first housing 41 with the other annular mating surface of the forming wall 42b of the second housing 42. Thus, the electric motor 2 is attached to the accommodating portion 43 of the transmission mechanism 8.

The shaft portion 8A of the input pulley 8a is connected to the shaft 2A extending into the housing portion 43 of the electric motor 2. For this purpose, the rack shaft 5 and its axis are parallel to the housing portion forming wall 41d of the first housing 41. A through hole 41f is formed, and the through hole 41f is a support portion that rotatably supports the shaft portion 8A of the input pulley 8a via a rotation collar 11 described later. The inner peripheral portion 41f1 continuing to the motor side opening having a slightly enlarged diameter and the inner peripheral portion 41f2 continuing to the slightly motor-reduced counter motor side opening are provided, and these inner peripheral portions 41f1 and 41f2 are made into perfect circles. The circular collars 11 are different in size, and the inner peripheral portions 41f1 and 41f2 are slidably fitted with the aforementioned rotary collar 11 in which the outer peripheral portion 11a is slidably rotated.

The rotating collar 11 includes a protruding outer peripheral portion 11b that protrudes from the through opening on the counter-motor side continuously to the outer peripheral portion 11a that is slidably rotated on the inner peripheral portions 41f1 and 41f2. Is formed with a male screw 11c over a predetermined width. Further, a motor for providing an axis O4 parallel to the rotation center O3 at a position eccentric from the rotation center O3 of the rotation collar 11 and rotatably supporting the shaft portion 8A of the input pulley 8a described above. A blind hole 11d having a circular cross section that is open only on the side is provided, and the shaft portion 8A of the input pulley 8a is rotatably supported in the blind hole 11d via bearings 13 and 14 that are two large and small radial ball bearings. The shaft portion 8A1 on the electric motor 2 side protrudes from the hole 11d through the opening of the blind hole 11d.

The input pulley 8a is integrally coupled to the protruding shaft portion 8A1 of the shaft portion 8A through the protruding boss portion 8a3, and at the same time, a serration 8a4 formed on the inner peripheral side of the main body portion 8a1 is connected to the electric motor. The ring member 2B fitted to the outer periphery of the shaft 2A is fitted to the serration 2B1 of the outer periphery of the ring member 2B and attached to the motor shaft 2A. Since the ring member 2B is fitted to the outer periphery of the motor shaft 2A by the serration 2B2, the input pulley 8a is attached to the outer periphery of the motor shaft 2A via double serration.

Accordingly, the pulley shaft portion 8A integrally coupled with the input pulley 8a is connected to the motor shaft 2A together with the input pulley 8a so as to rotate integrally and allow sliding in the axial direction. A lock nut 16 prevents the radial ball bearing 13 from moving.

The input pulley 8a is provided with a tooth portion 8a2 on the outer peripheral portion of the main body portion 8a1, and the main body of the output pulley 8b attached to the ball nut of the ball screw mechanism although not clearly shown in FIG. A tooth portion 8b2 is also provided on the outer peripheral portion of the portion 8b1, and a toothed belt 8c is stretched between the body portions 8a1 and 8b1 of the input and output pulleys 8a and 8b. Since this structure itself is the same as the structure in the first embodiment, further description is omitted.

  In the rotation collar 11, in the sliding contact rotation fitting to the inner peripheral portions 41f1 and 41f2 of the through holes, the male screw 11c of the outer peripheral portion 11b on the side opposite to the motor protrudes from the opening of the through hole 41f, and the outer peripheral portion 11b. When the lock nut 18 is screwed into the male screw 11c and the lock nut 18 is tightened, the rotation collar 11 is brought into a fixed state in which sliding rotation in the through hole 41f is impossible. A nut 19 for turning the collar 11 is provided by welding or the like on the side surface on the side opposite to the motor that substantially forms the blind hole 11d of the turning collar 11.

The tension adjustment of the belt 8 c in the adjustment unit 10 is performed in a state where the electric motor 2 is removed from the storage unit 43. First, the lock nut 18 fastened to the male screw 11c of the projecting outer peripheral portion 11b of the rotating collar 11 on the side opposite to the motor is loosened with a spanner, and then the color on the side of the rotating collar 11 on the side opposite to the motor. The rotation nut 19 is rotated by a spanner, and the sliding contact rotation in the through hole inner peripheral portions 41f1 and 41f2 of the rotation collar 11 is performed by an input pulley shaft whose rotation center line O4 is placed at an eccentric position. The part 8A is moved eccentrically by a predetermined amount. This eccentric movement of the input pulley shaft portion 8A by a predetermined amount adjusts the tension of the belt 8c stretched over the input pulley body portion 8a1.

Therefore, the tension of the belt 8c is appropriately adjusted by adjusting the rotation of the rotation collar 11 by an appropriate amount.
After adjusting the tension of the belt 8c, the lock nut 18 is tightened with a wrench, and the rotation collar 11 is fixed to the accommodating portion forming wall 41d of the first housing 41 so as not to slide and rotate in the through hole 41f. To do.

Then, after the rotation collar 11 is fixed by the lock nut 18, for example, perpendicular to the rotation axis O <b> 3 of the rotation collar 11 from a predetermined position outside the through hole 41 f outer peripheral structure portion of the housing portion forming wall 41 d of the first housing 41. The hole X2 that penetrates the outer peripheral structure portion of the through hole 41f from the outer diameter direction of the rotating collar 11 toward the rotating center O3 and reaches a predetermined depth of the thickness of the rotating collar 11 is drilled. Open, insert the knock pin 20 into the hole X2, hit with a hammer and fix it completely.

Then, the position of the electric motor 2 removed prior to the adjustment work is adjusted so that the axis of the shaft 2A coincides with the rotation center line O4 of the input pulley 8a after adjustment, and this adjustment position is maintained. The motor 2 is pushed so that the motor shaft 2A is slidably fitted to the inner peripheral portion of the input pulley 8a. As a result, the serration coupling via the ring member 2B causes the motor shaft 2A to be serrated and coupled to the input pulley 2a, that is, the input pulley shaft portion 8A so as to permit integral rotation and axial movement, and this state The motor 2 is held and attached to the forming wall 42a of the second housing 42, that is, to the transmission mechanism accommodating portion 43, thereby completing the tension adjustment operation of the belt 8c.

The structure of the electric power steering apparatus in the embodiment of the present invention is as described above.
Here, since the operation of the electric power steering apparatus in the first and second embodiments is almost common, the outline thereof will be briefly described.

As can be understood by referring to FIGS. 2, 3, 8, and the like, when the vehicle is in a straight traveling state and the steering force is not input to the input shaft 2 via the handle H and the steering shaft, the torsion bar 1 c is Since it does not twist, the torque sensor 1e does not issue an output signal, and the electric motor 2 that is drivingly connected to the input pulley 8a does not drive and does not output an auxiliary steering force. In this state, naturally, the output shaft 1d does not rotate either, so that the rack shaft 5 formed with the rack portion 5a meshing therewith does not move, and the steering force does not act on the wheels (not shown).

  When the vehicle is about to turn a curve and the steering wheel H is rotated and steered by the driver, the rotation of the steering wheel H causes the input shaft 1b, the torsion bar 1c, and the output shaft 1d to pass through an interlocking mechanism having a steering shaft. This is sequentially transmitted from the pinion 1f to the rack portion 5a, and the rack shaft 5 is reciprocated linearly in the longitudinal direction, and the wheel is rotated in a predetermined direction via the ball joint 6, the tie rod 7 and a steering mechanism (not shown). Rudder.

At the same time, the torsion bar 1c is twisted according to the steering force applied to the input shaft 1b, and a relative rotational phase difference is generated between the output shaft 1d and the input shaft 1b. This rotational phase difference is detected by the torque sensor 1e, and a signal corresponding to the direction of relative rotation and the magnitude of the phase difference is output.

Based on this output signal, the drive output of the electric motor 2 is controlled by the electronic control unit 1g, and the electric motor 2 generates a necessary output as an auxiliary steering force. This output is transmitted from the motor shaft 2A to the input pulley 8a through the coupling by the elastic joint 12C, and from the input pulley 8a to the output pulley 8b through the toothed belt 8c whose tension is appropriately adjusted by the adjusting unit 10 described above. Is transmitted (see FIG. 3).

The output from the electric motor 2 transmitted to the output pulley 8b is further transmitted to the ball nut 9a and the ball screw shaft 5b, and the rack shaft 5 is driven by the steering force based on the rotational steering of the driver handle H described above. A steering assist force is applied to the reciprocating linear motion in the longitudinal direction, thereby turning a wheel (not shown) for changing the direction of the vehicle by the rotational steering force of the handle H by the driver and the auxiliary steering force by the electric motor 2. Is made.

  Since the embodiment of the present invention is configured as described above, the following effects can be obtained.

That is, in the first embodiment, the tension adjusting unit 10 of the belt 8c is a long hole provided in the collar 11 that rotatably supports the input pulley 8a attached to the electric motor shaft 2A. The tension adjustment of 8c is performed by adjusting the relative position of the collar 11 with respect to the first housing 41, which is the collar mounting member, by the long hole, and screwing and fixing the collar 11 with the adjusting bolts B3 and B4 of the collar 11 after the position adjustment. Further, since the fixing by the knock pin 17 is performed, the structure for adjusting the tension of the belt 8c is simple, the adjustment work is easily performed, and the fixing by the adjusting bolts B3 and B4 and the double fixing by the knock pin 17 are performed. Therefore, the adjusted inter-axis distance is maintained even if the adjustment bolts B3 and B4 are loosened. Boss was the tension of the belt 8c is obtained, input, output pulley 8a, stable engagement of the belt tooth is maintained in 8b.

The electric motor 2 removed at the time of adjusting the tension of the belt 8c is assembled after the adjustment. The assembled motor 2 is disposed close to the head of the knock pin 17 into which the annular projecting portion 2c of the housing 2b is driven. Therefore, even if the knock pin 17 is loosened and pulled out, the head comes into contact with the annular projecting portion 2c, so that a predetermined amount can be suppressed.
Accordingly, even if the adjustment bolts B3 and B4 are loosened and the knock pin 17 is loosened, the meshing of the teeth of the belt 8c with the pulleys 8a and 8b is maintained, and the steering assist force can be generated. The function of the device is not lost.

In the second embodiment, the tension adjusting unit 10 of the belt 8c is a rotating collar 11 that rotatably supports the input pulley 8a attached to the electric motor shaft 2A at the eccentric position. The tension adjustment of the belt 8c by means of the relative adjustment of the eccentric position relative to the collar support member by the relative rotation with respect to the first housing 41 which is the color support member of the rotation collar 11, and after the position adjustment Since the rotation collar 11 is fixed to the collar support member by the lock nut 18 and the dowel pin 20, the structure for adjusting the tension of the belt 8 c is relatively simple. Since it is sufficient to simply rotate 11, it is simple and its workability is good.

Further, since the rotation collar 11 after the tension adjustment of the belt 8c is doubled by tightening with the lock nut 18 and fixing with the knock pin 20, the situation is such that the lock nut 18 is loosened. Even so, the adjusted tension of the belt 8c is reliably maintained.

1 is an overall view showing an electric power steering apparatus of the present invention. 1 is a schematic diagram showing an operation mechanism in steering of an electric power steering apparatus of the present invention. FIG. 2 is an enlarged longitudinal sectional view in the vicinity of an electric motor of the steering device in FIG. 1. It is a disassembled perspective view of 1 structural component of this invention. FIG. 2 is an enlarged side view of the vicinity of the electric motor of the steering device in FIG. 1, and a part thereof is shown in a cross-sectional view. It is a figure which shows the color of this invention, (a) is a front view (b) is a side view. It is explanatory drawing of tension adjustment of the belt by the collar of this invention. It is a figure which shows the 2nd Example of this invention, (a) is an expanded sectional view of an electric motor vicinity, (b) is AA sectional drawing in (a). It is a figure which shows the tension adjustment mechanism of the conventional belt. It is a figure which shows another example of the tension adjustment mechanism of the conventional belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gear box, 1a ... Steering force input part, 2 ... Electric motor, 2A ... Motor shaft, 3 ... Auxiliary steering force input part, 4 ... Gear housing, 41 ... -1st housing, 42 ... 2nd housing, 41d, 42b ... Transmission part accommodating part formation wall, 43 ... Transmission mechanism accommodating part, 5 ... Rack shaft, 5b ... Ball screw shaft 8, 8 ... Transmission mechanism, 8a ... Input pulley, 8A ... Input pulley shaft, 8b ... Output pulley, 8B ... Output pulley shaft, 8c ... Belt, 9 ... Ball screw mechanism, 9a ... ball nut, 10 ... adjusting part, 11 ... collar (rotating collar), 11A ... large diameter mounting part, 11A1 ... first mounting part, 11A2. ..Second mounting part, A11, A21... Binding site, A11a, A11b. Screw hole, A21a, A21b ... bolt insertion hole, 11B ... support part, 12 ... shaft coupling, 12C ... bushing, 17, 20 ... knock pin, X1, x2 ... for knock pin Hole, B, B1, B2 ... bolt, B3, B4 ... bolt (adjustment bolt).

Claims (2)

In an electric power steering apparatus that performs steering by giving an auxiliary steering force by driving an electric motor to a steering force by an operation of a steering via a belt transmission means,
The belt transmission means includes a belt tension adjusting portion, and the belt tension adjusting portion is a long hole provided in a collar that rotatably supports an input pulley attached to an electric motor shaft. The belt tension adjustment by the hole is performed by adjusting the relative position of the collar with respect to the collar mounting member by the long hole, screwing the collar bolt into the collar mounting member after the position adjustment, and fixing with a knock pin. Electric power steering device. In an electric power steering apparatus that performs steering by giving an auxiliary steering force by driving an electric motor to a steering force by an operation of a steering via a belt transmission means,
The belt transmission means includes a belt tension adjusting unit, and the belt tension adjusting unit is a rotating collar that rotatably supports an input pulley attached to the electric motor shaft at an eccentric position thereof. The belt tension is adjusted by the moving collar by adjusting the relative position of the eccentric position relative to the collar supporting member by rotating the rotating collar with respect to the collar supporting member, and locking the rotating collar with respect to the color supporting member after the position adjustment. An electric power steering device characterized by being fixed by a nut and a knock pin.

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